Re: [PATCH net-next 1/3] netdevsim: allow two netdevsim ports to be

[Jiri Pirko <jiri@resnulli.us>]

Thu, Dec 07, 2023 at 06:21:15PM CET, dw@davidwei.uk wrote:
>Add a debugfs file in
>/sys/kernel/debug/netdevsim/netdevsimN/ports/B/link

"peer" perhaps?

>
>Writing "M B" to this file will link port A of netdevsim N with port B of
>netdevsim M.
>
>Reading this file will return the linked netdevsim id and port, if any.
>
>Signed-off-by: David Wei <dw@davidwei.uk>
>---
> drivers/net/netdevsim/bus.c       | 10 ++++
> drivers/net/netdevsim/dev.c       | 97 +++++++++++++++++++++++++++++++
> drivers/net/netdevsim/netdev.c    |  5 ++
> drivers/net/netdevsim/netdevsim.h |  3 +
> 4 files changed, 115 insertions(+)
>
>diff --git a/drivers/net/netdevsim/bus.c b/drivers/net/netdevsim/bus.c
>index bcbc1e19edde..3e4378e9dbee 100644
>--- a/drivers/net/netdevsim/bus.c
>+++ b/drivers/net/netdevsim/bus.c
>@@ -364,3 +364,13 @@ void nsim_bus_exit(void)
> 	driver_unregister(&nsim_driver);
> 	bus_unregister(&nsim_bus);
> }
>+
>+struct nsim_bus_dev *nsim_bus_dev_get(unsigned int id)
>+{
>+	struct nsim_bus_dev *nsim_bus_dev;
>+	list_for_each_entry(nsim_bus_dev, &nsim_bus_dev_list, list) {
>+		if (nsim_bus_dev->dev.id == id)
>+			return nsim_bus_dev;
>+	}
>+	return NULL;
>+}
>diff --git a/drivers/net/netdevsim/dev.c b/drivers/net/netdevsim/dev.c
>index b4d3b9cde8bd..72ad61f141a2 100644
>--- a/drivers/net/netdevsim/dev.c
>+++ b/drivers/net/netdevsim/dev.c
>@@ -25,6 +25,7 @@
> #include <linux/mutex.h>
> #include <linux/random.h>
> #include <linux/rtnetlink.h>
>+#include <linux/string.h>
> #include <linux/workqueue.h>
> #include <net/devlink.h>
> #include <net/ip.h>
>@@ -388,6 +389,99 @@ static const struct file_operations nsim_dev_rate_parent_fops = {
> 	.owner = THIS_MODULE,
> };
> 
>+static ssize_t nsim_dev_link_read(struct file *file, char __user *data,
>+				  size_t count, loff_t *ppos)
>+{
>+	struct nsim_dev_port *nsim_dev_port;
>+	struct netdevsim *peer;
>+	unsigned int id, port;
>+	char buf[11];

See below.


>+	ssize_t len;
>+
>+	nsim_dev_port = file->private_data;
>+	peer = nsim_dev_port->ns->peer;
>+	if (!peer) {
>+		len = scnprintf(buf, sizeof(buf), "\n");
>+		goto out;
>+	}
>+
>+	id = peer->nsim_bus_dev->dev.id;
>+	port = peer->nsim_dev_port->port_index;
>+	len = scnprintf(buf, sizeof(buf), "%u %u\n", id, port);
>+
>+out:
>+	return simple_read_from_buffer(data, count, ppos, buf, len);
>+}
>+
>+static ssize_t nsim_dev_link_write(struct file *file,
>+					  const char __user *data,
>+					  size_t count, loff_t *ppos)
>+{
>+	struct nsim_dev_port *nsim_dev_port, *peer_dev_port;
>+	struct nsim_bus_dev *peer_bus_dev;
>+	struct nsim_dev *peer_dev;
>+	unsigned int id, port;
>+	char *token, *cur;
>+	char buf[10];

# echo "889879797" >/sys/bus/netdevsim/new_device
# devlink dev
netdevsim/netdevsim889879797

I don't think that 10/11 is enough.




>+	ssize_t ret;
>+
>+	if (count >= sizeof(buf))
>+		return -ENOSPC;
>+
>+	ret = copy_from_user(buf, data, count);
>+	if (ret)
>+		return -EFAULT;
>+	buf[count] = '\0';
>+
>+	cur = buf;
>+	token = strsep(&cur, " ");

Why you implement this differently, comparing to new_device_store()?
Just use sscanf(), no?


>+	if (!token)
>+		return -EINVAL;

In general, in case of user putting in invalid input, please hint him
the correct format. Again, see new_device_store().


>+	ret = kstrtouint(token, 10, &id);
>+	if (ret)
>+		return ret;
>+
>+	token = strsep(&cur, " ");
>+	if (!token)
>+		return -EINVAL;
>+	ret = kstrtouint(token, 10, &port);
>+	if (ret)
>+		return ret;
>+
>+	/* too many args */
>+	if (strsep(&cur, " "))
>+		return -E2BIG;
>+
>+	/* cannot link to self */
>+	nsim_dev_port = file->private_data;
>+	if (nsim_dev_port->ns->nsim_bus_dev->dev.id == id)

Why not? Loopback between 2 ports of same device seems like completely
valid scenario.


>+		return -EINVAL;
>+
>+	/* invalid netdevsim id */
>+	peer_bus_dev = nsim_bus_dev_get(id);
>+	if (!peer_bus_dev)
>+		return -EINVAL;
>+
>+	peer_dev = dev_get_drvdata(&peer_bus_dev->dev);
>+	list_for_each_entry(peer_dev_port, &peer_dev->port_list, list) {
>+		if (peer_dev_port->port_index == port) {
>+			nsim_dev_port->ns->peer = peer_dev_port->ns;
>+			peer_dev_port->ns->peer = nsim_dev_port->ns;
>+			return count;
>+		}
>+	}
>+
>+	return -EINVAL;
>+}
>+
>+static const struct file_operations nsim_dev_link_fops = {
>+	.open = simple_open,
>+	.read = nsim_dev_link_read,
>+	.write = nsim_dev_link_write,
>+	.llseek = generic_file_llseek,
>+	.owner = THIS_MODULE,
>+};
>+
> static int nsim_dev_port_debugfs_init(struct nsim_dev *nsim_dev,
> 				      struct nsim_dev_port *nsim_dev_port)
> {
>@@ -418,6 +512,9 @@ static int nsim_dev_port_debugfs_init(struct nsim_dev *nsim_dev,
> 	}
> 	debugfs_create_symlink("dev", nsim_dev_port->ddir, dev_link_name);
> 
>+	debugfs_create_file("link", 0600, nsim_dev_port->ddir,
>+			    nsim_dev_port, &nsim_dev_link_fops);
>+
> 	return 0;
> }
> 
>diff --git a/drivers/net/netdevsim/netdev.c b/drivers/net/netdevsim/netdev.c
>index aecaf5f44374..1abdcd470f21 100644
>--- a/drivers/net/netdevsim/netdev.c
>+++ b/drivers/net/netdevsim/netdev.c
>@@ -388,6 +388,7 @@ nsim_create(struct nsim_dev *nsim_dev, struct nsim_dev_port *nsim_dev_port)
> 	ns->nsim_dev = nsim_dev;
> 	ns->nsim_dev_port = nsim_dev_port;
> 	ns->nsim_bus_dev = nsim_dev->nsim_bus_dev;
>+	ns->peer = NULL;
> 	SET_NETDEV_DEV(dev, &ns->nsim_bus_dev->dev);
> 	SET_NETDEV_DEVLINK_PORT(dev, &nsim_dev_port->devlink_port);
> 	nsim_ethtool_init(ns);
>@@ -409,6 +410,10 @@ void nsim_destroy(struct netdevsim *ns)
> 	struct net_device *dev = ns->netdev;
> 
> 	rtnl_lock();
>+	if (ns->peer) {
>+		ns->peer->peer = NULL;
>+		ns->peer = NULL;

What is this good for?


>+	}
> 	unregister_netdevice(dev);
> 	if (nsim_dev_port_is_pf(ns->nsim_dev_port)) {
> 		nsim_macsec_teardown(ns);
>diff --git a/drivers/net/netdevsim/netdevsim.h b/drivers/net/netdevsim/netdevsim.h
>index 028c825b86db..ac7b34a83585 100644
>--- a/drivers/net/netdevsim/netdevsim.h
>+++ b/drivers/net/netdevsim/netdevsim.h
>@@ -125,6 +125,7 @@ struct netdevsim {
> 	} udp_ports;
> 
> 	struct nsim_ethtool ethtool;
>+	struct netdevsim *peer;
> };
> 
> struct netdevsim *
>@@ -417,3 +418,5 @@ struct nsim_bus_dev {
> 
> int nsim_bus_init(void);
> void nsim_bus_exit(void);
>+
>+struct nsim_bus_dev *nsim_bus_dev_get(unsigned int id);
>-- 
>2.39.3
>
>